The field of the disclosure relates generally to electrical circuit protection devices, and more particularly, to insulation for molded case circuit breakers.
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overloaded or shorted circuits. A coupler mechanism of the circuit breaker can be actuated to open and close contacts to which a load is connected. Circuit breakers have an over-current trip unit that provides over-current protection.
Electrical power enters a circuit breaker through a line strap. An insulator is used to prevent an electrical path from the line strap to any surrounding electrically conductive parts of the circuit breaker. Typically, when a contact arm of a circuit breaker is separated from the line strap during an off or “tripped” position, the line strap is at the closest point to the contact arm. Due to the line strap being close to the contact arm in the off position, electricity only needs to travel a short distance between the contact arm and the line strap to reconnect and continue the electrical current path to the armature, thus an insulative barrier is used to prevent this electrical path from reconnecting in the off position. Commonly, a voltage resistance, or breakdown test, is used to define the paths. Typically, as voltage of the line strap increases, a larger separation of the line strap and the contact arm is required to prevent the electrical path from forming. Conventionally, due to geometric and size restraints of circuit breakers, a barrier such as dielectric resistive gel (e.g., silicon rubber gel), or resistive tape is used to increase the voltage resistance of the insulator, but too much of the line strap is commonly exposed to be effectively insulated with the resistive gel, such as room temperature vulcanizing (RTV) silicon rubber gel. Such process of applying resistive gel is typically applied manually by an operator, and as such, the application of the resistive gel is operator dependent and not effectively repeatable.